I found it odd that nothing ever spawned on the rooftops of hospitals while it was very accessable and there was loot there in the mod. So I opened up my inventory screen and walked along the edge, and I actually found loot there through the vincinity tab. I came to the conclusion that the loot items are hidden under the floor.

video: https://www.youtube.com/watch?v=RvhWjrQjhIo